Offset leg framing element for fire stop applications

ABSTRACT

The invention disclosed herein is directed to an offset leg framing element for use in a fire rated assembly and comprises: a web section having opposing edges; a pair of outwardly extending sidewalls integrally connected to the web, wherein the sidewalls are substantially parallel and confront each other. In addition, at least one laterally extending ledge section is integrally connected to one of the pair of outwardly extending sidewalls; and at least one downwardly extending leg is integrally connected to the at least one ledge section. The offset leg framing element may be characterized in that the ratio the sidewall height (h 1 ) over the ledge section width (w 2 ) is greater than or equal to one (h 1/ w 2 ≧1), and wherein the ratio the sidewall height (h 1 ) over the web section width (w 1 ) is greater than or equal to one sixth (h 1/ w 1 ≧0.1667).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Provisional Application No. 61/309,994 filed on Mar. 3, 2010, which application is incorporated herein by reference in its entirety for all purposes.

TECHNICAL FIELD

The present invention relates generally to structural wall framing elements and, more particularly, to structural wall framing elements that are sized and dimensioned to facilitate the application of a spray-on fire resistant coating to an underlying support beam substrate and the construction of fire rated partitions, as well as to related wall assemblies.

BACKGROUND OF THE INVENTION

Metal framing assemblies are commonly used to construct commercial and residential buildings in the building construction industry. Such metal framing assemblies are generally constructed from a plurality of metal framing members including studs, joist, trusses, and other metal posts and beams formed from sheet metal and frequently fabricated to have the same general cross-sectional dimensions as standard wood members used for similar purposes. Metal framing members are typically constructed by roll-forming 12 to 24 gauge galvanized sheet steel. Although many cross-sectional shapes are available, the primary shapes used in building construction are C-shaped studs and U-shaped tracks.

In common practice, a wall to ceiling connection of many newly constructed buildings consists essentially of an inverted U-shaped elongated steel channel member (or track) configured to receive steel studs between the legs (also sometimes referred to as sidewalls or flanges) of the shaped channel A wallboard is generally attached to at least one side of the studs. The studs and wallboard are in many instances spaced apart from the ceiling a short gap distance in order to allow for ceiling deflections caused by seismic activity or moving overhead loads. Channel and stud assemblies that allow for ceiling deflections are commonly referred to as dynamic head-of-wall systems. Exemplary steel stud wall constructions may be found in U.S. Pat. Nos. 4,854,096 and 4,805,364 both to Smolik, and U.S. Pat. No. 5,127,203 to Paquette. Exemplary dynamic head-of-wall systems having steel stud wall constructions may be found in U.S. Pat. No. 5,127,760 to Brady, and U.S. Pat. No. 6,748,705 to Orszulak et al.

In order to contain the spread of smoke and fire, a fire resistant material such as, for example, mineral wool is often times stuffed into the gaps between the ceiling and wallboard (see, e.g., U.S. Pat. No. 5,913,788 to Herren). For example, mineral wool is often stuffed between a steel header track (e.g., an elongated U-shaped channel) and a corrugated steel roof deck (used in many types of steel and concrete building constructions); a fire resistant and generally elastomeric spray coating is then applied onto the exposed mineral wool to thereby form a fire resistant joint seal (see, e.g., U.S. Pat. No. 7,240,905 to Stahl). In certain situations where the ceiling to wallboard gap is relatively small, a fire resistant and elastomeric caulk is commonly applied so as to fill any small gaps. In still another approach and as disclosed in U.S. Pat. Nos. 5,471,805 and 5,755,066 both to Becker, a slidable noncombustible secondary wall member is fastened to an especially configured steel header track and immediately adjacent to the wallboard. In this configuration, the secondary wall member provides a fire barrier that is able to accommodate ceiling deflections. All of these approaches, however, are relatively labor intensive and thus expensive.

Intumescent materials have long been used to seal certain types of construction gaps such as, for example, conduit through-holes. In this regard, intumescent and fire barrier materials (often referred to as firestop materials or fire retardant materials) have been used to reduce or eliminate the passage of smoke and fire through openings between walls and floors and the openings caused by through-penetrations (i.e., an opening in a floor or wall which passes all the way through from one room to another) in buildings, such as the voids left by burning or melting cable insulation caused by a fire in a modern office building. Characteristics of fire barrier materials suitable for typical commercial fire protection use include flexibility prior to exposure to heat, the ability to insulate and/or expand, and the ability to harden in place upon exposure to fire (i.e., to char sufficiently to deter the passage of heat, smoke, flames, and/or gases). Although many such materials are available, the industry has long sought better and more effective uses of these materials and novel approaches for better fire protection, especially in the context of dynamic head-of-wall construction joints and gaps.

In order to achieve a specified fire rating set forth by applicable building and/or fire codes, many structural support beams (e.g., I-beams and other related substrate surfaces) are, after they are erected, treated with a spray-on fire resistant coating prior to assembly of the internal walls. In most instances and depending on the required hourly fire rating, the thickness of the spray-on fire resistant coating generally ranges from about ⅜ inch up to about 1 inch. In addition, sheet-metal wall assemblies and other partitions are often constructed such that one end of the wall or partition intersects at a structural support beam that has been treated with a spray-on fire resistant coating. In order to provide a hard surface for attachment of a sheet-metal stud or track (that forms an integral part of a wall assembly), a plurality of spaced apart “Z-clips” are in common practice first attached along the structural support beam at regular intervals before application of the spray-on fire resistant coating. The use of Z-clips provides a simply solution in this regard, but the use of Z-clips in this manner is time consuming, labor intensive, and inefficient.

Although many advances have been made with respect to the design of new and alternative types of framing elements and structures useful to prevent the spread of fire and/or smoke in a building, there is still a need in the art for structural wall framing elements and related structural wall assemblies that better prevent the spread of fire and/or smoke. The present invention fulfills these needs and provides for further related advantages.

SUMMARY OF THE INVENTION

In brief, the present invention in an embodiment is directed to an offset leg framing element for use in a fire rated assembly. The offset leg framing element comprises a web section having opposing edges; a pair of outwardly extending sidewalls integrally connected to the web, wherein each sidewall has a proximal end and a distal end, and wherein the proximal end of each sidewall is integrally connected to one of the opposing edges of the web, and wherein the sidewalls are substantially parallel and confront each other. The offset leg framing element also comprises at least one laterally extending ledge section integrally connected to one of the pair of outwardly extending sidewalls, wherein the at least one ledge section has an inner edge and an outer edge, and wherein the inner edge of the at least one leg section is integrally connected to the distal end of one of the pair of sidewalls; and at least one downwardly extending leg integrally connect to the at least one ledge section, wherein the at least one leg has a proximal end and a distal end, and wherein the proximal end of the at least one leg is integrally connected to the outer edge of the at the at least one ledge section.

In further embodiments, the offset leg framing element may be characterized in that the distance between the opposing edges of the web section defines a web section width (w₁), and wherein the distance between the proximal and distal ends of at least one of the pair of sidewalls defines a sidewall height (h₁), and the distance between the inner and outer edges of the at least one ledge section defines a ledge section width (w₂), and wherein the ratio the sidewall height (h₁) over the ledge section width (w₂) is greater than or equal to one (h_(1/)w₂≧1), and wherein the ratio the sidewall height (h₁) over the web section width (w₁) is greater than or equal to one sixth (h_(1/)w₁≧0.0625).

In still further embodiments, the offset leg framing element further comprises an outwardly facing intumescent material positioned lengthwise on an outer portion of the least one leg. In addition, the outer portion of the least one leg has a proximal section adjacent to the at least one ledge, and a distal section adjacent to the proximal section and the distal end of the at least one leg, and wherein the intumescent material is positioned on the proximal section of the at least one leg. Finally, a plurality of vertically aligned slots may be positioned along the distal section of at least one of the legs.

These and other aspects, advantages and features of the present invention will become apparent from the detailed description set forth below, from the accompanying drawings, from the claims, and from principles that are embodied in the specific structures that are illustrated and described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Like reference numerals are used to designate like parts and features throughout the several views of the drawings.

FIG. 1A is an end view of an offset leg framing element sized and dimensioned for use in fire stop applications in accordance with an embodiment of the present invention.

FIG. 1B is a partial perspective view of the offset leg framing element shown in FIG. 1A.

FIG. 2 is a side cross-sectional view of a structural support I-beam attached to a ceiling and having an attached downwardly projecting offset leg framing element that forms part of a wall assembly in accordance with an embodiment of the present invention.

FIG. 3 is a top cross-sectional view of a structural support I-beam having an attached laterally projecting offset leg framing element that forms part of a wall assembly in accordance with an embodiment of the present invention.

FIG. 4 is a partial perspective view of an offset leg framing element that includes a plurality slots in each offset leg in accordance with an embodiment of the present invention.

FIG. 5 is a partial perspective view of an offset leg framing element that includes a plurality slots on each offset leg in accordance with an embodiment of the present invention.

FIG. 6 is a partial perspective view of an offset leg framing element that includes an intumescent material positioned on an upper portion of each offset leg in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals are used to designate like parts and features, the present invention in a first embodiment (and as best shown in FIGS. 1A-B) is directed to an offset leg framing element for use in a fire rated assembly (of a building). The offset leg framing element 10 comprises a web section 12 having opposing edges 14, 16, and a pair of outwardly extending sidewalls 18, 20 integrally connected to the web section 12. As shown, each sidewall 18, 20 has a proximal end 22 and a distal end 24, wherein the proximal end 22 of each sidewall 18, 20 is integrally connected to one of the opposing edges 14, 16 of the web section 12, and wherein the sidewalls 18, 20 are substantially parallel and confront each other.

The offset leg framing element 10 also comprises at least one laterally extending ledge section 26 integrally connected to one of the pair of outwardly extending sidewalls 18, 20. As shown, the at least one ledge section 26 has an inner edge 28 and an outer edge 30, and wherein the inner edge 28 of the at least one ledge section 26 is integrally connected to the distal end 24 of one of the pair of sidewalls 18, 20. In addition, at least one downwardly extending leg 32 is integrally connected to the at least one ledge section 26, wherein the at least one leg 32 has a proximal end 34 and a distal end 36, and wherein the proximal end 34 of the at least one leg 32 is integrally connected to the outer edge 30 of the at the at least one ledge section 26. In this configuration, the at least one leg 32 is considered to be an “offset” leg.

In order facilitate the application of a spray-on fire resistant coating, the offset leg framing element 10 needs to be properly sized and dimensioned. In this regard, the offset leg framing element 10 may be characterized in that the distance between the opposing edges 14, 16, of the web section 12 defines a web section width (w₁), and wherein the distance between the proximal and distal ends 22, 24 of at least one of the pair of sidewalls 18, 20 defines a sidewall height (h₁), and the distance between the inner and outer edges 28, 30 of the at least one ledge section 26 defines a ledge section width (w₂), and wherein the ratio the sidewall height (h₁) over the ledge section width (w₂) is greater than or equal to one (h_(1/)w₂≧1), and wherein the ratio the sidewall height (h₁) over the web section width (w₁) is greater than or equal to one sixth (h_(1/)w₁≧0.0625).

More generally, the web section width (w₁) preferably ranges from about 2 to 6 inches, and more preferably from about 2.5 to 4.5 inches. The sidewall height (h₁) is preferably about the same as the average thickness (t₁) of the applied fire resistant coating, or about ⅜ to 2 inches, and preferably is about 1 inch. Finally, the ledge section width (w₂) preferably ranges from about 0.5 to 1 inch, and more preferably is about 0.75 inches. In typical construction, the desired profile associated with each properly sized and dimensioned offset leg framing element 10 may be made by roll-forming 12 to 24 gauge galvanized sheet steel, and more preferably 16 to 20 gauge galvanized sheet steel.

In still further embodiments, the offset leg framing element 10 further comprises an outwardly facing intumescent material 38 positioned lengthwise on an outer portion of the least one leg 32. In addition (and as best shown in FIGS. 4-6), the outer portion of the least one leg 32 has a proximal section 40 adjacent to the at least one ledge 26, and a distal section 42 adjacent to the proximal section 40 and the distal end 36 of the at least one leg 32, and wherein the intumescent material 38 is positioned on the proximal section 40 of the at least one leg 32. Finally a plurality of vertically aligned slots 44 may be positioned along the distal section 42 of at least one of the legs 32.

The present invention in another embodiment (and as best shown in FIGS. 2 and 3) is directed to an offset leg framing element 10 in combination with an elongated support beam 8 for use in a fire rated assembly, wherein the support beam 8 has an applied fire resistant coating 6 on most of its sides, and wherein the applied fire resistant coating 6 has an average thickness (t₁). As shown in FIG. 2, an elongated support beam 8 (I-beam) has been attached to the bottom section of a concrete 11 filed corrugated roof deck pan 9, and an offset leg framing element 10 has been attached to a bottom surface of the support beam 8. A fire resistant coating 6 has then been applied about the support beam 8 and such that it contacts the pair of sidewalls 18, 20. In this configuration, a wall fire rated assembly that includes studs 13 and wallboard 15 may be efficiently constructed. As shown in FIG. 3, an elongated support beam 8 (I-beam) has been utilized as a post, but similarly has an offset leg framing element 10 attached to a side surface of the support beam 8. As before and this alternative configuration, a fire rated wall assembly that includes studs 13 and wallboard 15 may be efficiently constructed.

The intumescent strip 38 component of the present invention is commercially available (e.g., 3M Company or The Rectorseal Corporation, U.S.A.) and preferably has an adhesive backing that allows it to be readily affixed onto the outer sidewall surface. Exemplary in this regard are the heat expandable compositions disclosed in U.S. Pat. No. 6,207,085 to Ackerman (incorporated herein by reference), which discloses a composition that, when subjected to heat, expands to form a heat-insulating barrier. A preferred composition contains expandable graphite (˜10-40 wt %), a fire retardant (˜10-40 wt %), and an optional inorganic intumescent filler (<50 wt %), all of which are admixed together with a resinous emulsion (˜30-60 wt %). The expandable graphite is generally manufactured by the oxidation of graphite flake in sulfuric acid (with such intercalated graphite being swellable or expandable up to about 100 times of its original volume when heated at high temperature). The fire retardant generally includes amine/phosphorous containing salts such as, for example, amine salts of phosphoric acid or lower alkyl esters thereof. A preferred fire retardant is a C₂-C₈ alkyl diamine phosphate. Intumescent activation or expansion generally begins at about 392° F. In order to ensure that the intumescent strip stays in place when exposed to heat, it has been found that a commercially available (e.g., 3M Company, U.S.A.) fire-retardant epoxy adhesive may preferably also be used. In other words, a fire-retardant adhesive (not shown) may be interposed between the intumescent strip and the outer sidewall surfaces of the pair of sidewalls. In some embodiments, the intumescent strip may on its top surface include a protective foil tape or polymeric coating to protect the underlying intumescent material from degradation that may occur due to wall or partition cycling.

While the present invention has been described in the context of the embodiments illustrated and described herein, the invention may be embodied in other specific ways or in other specific forms without departing from its spirit or essential characteristics. Therefore, the described embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing descriptions, and all changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope. 

1. An offset leg framing element for use in a fire rated assembly, comprising: a web section having opposing edges; a pair of outwardly extending sidewalls integrally connected to the web section, wherein each sidewall has a proximal end and a distal end, and wherein the proximal end of each sidewall is integrally connected to one of the opposing edges of the web section, and wherein the sidewalls are substantially parallel and confront each other; at least one laterally extending ledge section integrally connected to one of the pair of outwardly extending sidewalls, wherein the at least one ledge section has an inner edge and an outer edge, and wherein the inner edge of the at least one ledge section is integrally connected to the distal end of one of the pair of sidewalls; and at least one downwardly extending leg integrally connected to the at least one ledge section, wherein the at least one leg has a proximal end and a distal end, and wherein the proximal end of the at least one leg is integrally connected to the outer edge of the at the at least one ledge section.
 2. The offset leg framing element of claim 1 wherein the distance between the opposing edges of the web section defines a web section width (w₁), and wherein the distance between the proximal and distal ends of at least one of the pair of sidewalls defines a sidewall height (h₁), and the distance between the inner and outer edges of the at least one ledge section defines a ledge section width (w₂), and wherein the ratio the sidewall height (h₁) over the ledge section width (w₂) is greater than or equal to one (h_(1/)w₂≧1), and wherein the ratio the sidewall height (h₁) over the web section width (w₁) is greater than or equal to one sixth (h_(1/)w₁≧0.1667).
 3. The offset leg framing element of claim 2, further comprising an outwardly facing intumescent material positioned lengthwise on an outer portion of the least one leg.
 4. The offset leg framing element of claim 3 wherein the outer portion of the least one leg has a proximal section adjacent to the at least one ledge, and a distal section adjacent to the proximal section and the distal end of the at least one leg, and wherein the intumescent material is positioned on the proximal section of the at least one leg.
 5. The offset leg framing element of claim 4, further comprising a plurality of vertically aligned slots positioned along the distal section of at least one of the legs.
 6. An offset leg framing element in combination with an elongated support beam for use in a fire rated assembly, wherein the support beam has an applied fire resistant coating on most of its sides, and wherein the applied fire resistant coating has an average thickness (t₁), comprising: an elongated offset leg framing element attached lengthwise and positioned immediately adjacent to the elongated support beam along a section of the support beam that does not have an applied fire resistant coating thereon; an elongated web section of the offset leg framing element having opposing edges, wherein the elongated web section is attached lengthwise to the elongated support beam along the section of the support beam that does not have an applied fire resistant coating thereon; a pair of outwardly extending sidewalls integrally connected to the web and in contact with the applied fire resistant coating, wherein each sidewall has a proximal end and a distal end, and wherein the proximal end of each sidewall is integrally connected to one of the opposing edges of the web, and wherein the sidewalls are substantially parallel and confront each other; at least one laterally extending ledge section integrally connected to one of the pair of outwardly extending sidewalls, wherein the at least one ledge section has an inner edge and an outer edge, and wherein the inner edge of the at least one leg section is integrally connected to the distal end of one of the pair of sidewalls; and at least one downwardly extending leg integrally connect to the at least one ledge section, wherein the at least one leg has a proximal end and a distal end, and wherein the proximal end of the at least one leg is integrally connected to the outer edge of the at the at least one ledge section.
 7. The offset leg framing element of claim 6 wherein the distance between the opposing edges of the web section defines a web section width (w₁), and wherein the distance between the proximal and distal ends of at least one of the pair of sidewalls defines a sidewall height (h₁), and the distance between the inner and outer edges of the at least one ledge section defines a ledge section width (w₂), and wherein the ratio the sidewall height (h₁) over the ledge section width (w₂) is greater than or equal to one (h_(1/)w₂≧1), and wherein the ratio the sidewall height (h₁) over the web section width (w₁) is greater than or equal to one sixth (h_(1/)w₁≧0.0625), and wherein the thickness (t₁) of the applied fire resistant coating is about equal to the sidewall height (h₁) (t₁≈h₁).
 8. The offset leg framing element of claim 7, further comprising an outwardly facing intumescent material 38 positioned lengthwise on an outer portion of the least one leg.
 9. The offset leg framing element of claim 8 wherein the outer portion of the least one leg has a proximal section adjacent to the at least one ledge, and a distal section adjacent to the proximal section and the distal end of the at least one leg, and wherein the intumescent material is positioned on the proximal section of the at least one leg.
 10. The offset leg framing element of claim 9, further comprising a plurality of vertically aligned slots positioned along the distal section of at least one of the legs. 